5) Pulmonary Dynamics Flashcards
Ventilatory Breakpoint
Point where VE and VCO2 incr disproportionately w/ VO2 during graded exercise
- aka anaerobic threshold (55% of VO2max)
Lactate Threshold
The highest VO2 or exercise intensity before a 1.0mM incr in blood lactate concentration above resting
How is VT measured?
Non-invasively through a metabolic cart
How is lactate threshold measured?
Invasively through blood work
What does cigarette smoking do to HR during exercise and why?
Blunts HR response → Alters sensitivity of autonomic neural control
Desribe the energetic cost of breathing in pt’s w/COPD
- Normal cost of breathing at rest is tripled bc of respiratory resistance
- Severely limits the exercise capacity
What percentage of total exercise VO2 does energetic cost of breathing equal in pt’s w/COPD?
40%
For pt’s w/COPD how can exercise training change PFT?
Small Improvements, however it can still:
- Incr exercise capacity
- Improve respiratory fxn
- Improve peripheral muscle fxn
- Decr dyspnea
At rest, what controls the respiratory cycle?
Automatic activity of inspiratory neurons → Cell bodies in the medulla respond to incr in paCO2 and H+
Is inspiration active or passive?
Active
At rest, what regulates pulmonary ventilation?
Chemical state of blood
Describe the process that occurs for the body to incr ventilation
- Decr O2 stims peripheral chemoreceptors
- Aortic and carotid chemoreceptors react to icnr ventilation
Should paO2 decr in a healthy person?
No
Besides reduced O2 pressures, what else do peripheral chemoreceptors incr ventilation in response to?
- Incr paCO2
- Incr temp
- Low BP
- Metabolic acidosis
- Changes in H+
- Exercise
What is the most important stimulus for a healthy person at rest and why?
paCO2 → Small incr in paCO2 can cause a large incr in VE
What stims pt’s w/COPD to breath
Hypoxic Drive (Low O2)
What is the most stressful physiologic activity
Coughing
Why does alveolar ventilation incr?
To maintain proper gas concentrations for rapid gas exchange
Describe ventilatory, VO2, and VCO2 pattern during light and moderate exercise
Incr linearly
For every L of consumed O2, how much air are we taking in?
20-25L
Ventilatory Equivalent
VE:VO2 ratio
- Should be 25:1 during submax exercise (up to 55% of VO2max)
Onset of Blood Lactate Accumulation (OBLA)
The exercise level when LA starts to systemically incr above resting level (4.0mM)
- Relates to onset of anaerobiosis and the subsequent accumulation of LA
- The more muscle mass used, the high the VO2 OBLA will occur at
At OBLA, what process supplies energy?
Glycolysis
What percent of VO2max does OBLA occur at in untrained and trained individuals?
- Untrained = 55-65%
- Trained = >70%
